The World of Warcraft Website announces the Mists of Pandaria beta test is live in Blizzard's MMORPG. They say those selected to participate will receive an email invitation , though they warn to remain vigilant for potential phishing attempts. There is no NDA involved, so this will likely provoke a flood of previews and media. Here's more on the testing:

The World of Warcraft®: Mists of Pandaria™ beta test has begun! Over the course of the test, we’ll be inviting Annual Pass holders, press, fansites, friends and family, and opt-in beta testers to participate. This first phase of the beta focuses on the 1-10 starting experience for new Pandaren. High-level content as well as template characters will become available in future beta updates, but you can still copy over your own high level characters now if you’d like to test the new talent system.